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Apply percent concepts to consumer math, including finding final prices after taxes and discounts.
Have you ever reached the checkout counter with exactly 18.99 item actually costs more because of sales tax? Understanding how percentages work in the real world is like having a superpower that protects your wallet.
When you buy something or eat at a restaurant, the price you see isn't always the price you pay. Sales tax and tips are additional costs added to the original price. Think of the original price as . If you add a sales tax, you are actually paying of the original cost. To calculate this quickly, convert the percentage to a decimal and multiply. For example, a tax becomes . You can find the tax by multiplying the price by , then adding it to the original, or simply multiply the original price by to get the total in one step.
You order pizza for and want to leave a tip.
1. Convert the tip percentage to a decimal: . 2. Multiply the price by the decimal: . 3. Add the tip to the original price: .
Alternatively: .
Quick Check
If a video game costs $50 and the sales tax is 8%, what is the total cost?
Answer
$54
A discount is a reduction in the original price. When a store has a sale, they take a percentage off. If an item is off, you are 'saving' , which means you are 'paying' of the original price (). This is called the sale price. Just like with tax, you can calculate the discount amount first and subtract it, or you can multiply the original price by the percentage you are actually paying to find the sale price directly.
A pair of sneakers originally costs but is on sale for off.
1. Find the percentage you pay: . 2. Convert to a decimal: . 3. Multiply the original price by the decimal: .
The sale price is .
Quick Check
A $120 jacket is 25% off. How much money do you save (the discount amount)?
Answer
$30
In the real world, you often deal with a discount and tax at the same time. The most important rule to remember is: Apply the discount first, then calculate tax on the sale price. Stores don't charge you tax on the money you saved! This is a multi-step process. First, find the reduced price after the discount. Second, use that new number to calculate the tax or tip. Even though it seems like the percentages might 'cancel out' if they are the same, they won't, because they are being calculated on different totals.
You buy a tablet for . It is on sale for off, and there is a sales tax.
1. Calculate the sale price: . 2. Calculate the tax on the sale price: . 3. Add the tax to the sale price: .
Final total: .
A backpack costs $40. If the sales tax is 5%, what is the total price?
A skateboard is on sale for 20% off. The original price was $150. What is the sale price?
When calculating the final cost of a discounted item with tax, you should add the tax to the original price before taking the discount.
Review Tomorrow
In 24 hours, try to explain to a friend why a 10% discount followed by a 10% tax doesn't result in the original price.
Practice Activity
Next time you go to a store or restaurant, look at the receipt. Try to calculate the tax or tip manually before looking at the total!